How to use rex to extract a named field within a named field?

[jpaulovich]

Greetings, The event that I'm working with is below. The problem is that our platform (in this case) has a field called 'parm', which Splunk extracts. However, I need to extract the field as 'mobileNetworkCode' with the associated values. Sadly, my efforts to accomplish this using rex have not been successful. The part that I'm having trouble with is properly extracting the field values (260 in this example). Any assistance is certainly appreciated.

​MobileApi.1.tue:1018 23:01:31.87: [MobileApiThread1]  >> tan_lookup3_q handle=33 contextid=aab81b0d1fb8969 sessionid=0 classid=14072 ani=NNNNNNNNNNN method=8 type=1 lock_time=60 map_time=60 svc_id=5718352036 controlNumber=4435209740 dn=+NNNNNNNNNNN rawdn=+NNNNNNNNNNN aniBlocked= otg=AND-TANSPA_X sctype=1 cac= isCustServ=false locked=false callAni=NNNNNNNNNN country=US callsetupid=0a1823013187aac **parm=mobileNetworkCode=260** mobileCountryCode=310 mobileCarrierName=XXXXXXXX

[jpaulovich]

These both worked fine. I was curious about runDuration ...
Surprisingly, "rex field=parm "=(?[\S]+)" ran for 5.112s, while
rex field=_raw "(?i)parm=mobileNetworkCode=(?P\d+) ran for 4.449s. I would have thought the rex using the specific field would have been quicker. In this case though, it's only an academic point.
Thank you very much for your excellent, expeditious explanations 🙂

One other (quick?) question (related to this search)...
Splunk is chopping a specific field value at the & (ampersand), i.e. ABCXYZ&123456, and returns only ABCXYZ. How can I coax Splunk to return the entire field contents, which includes the &?

[JDukeSplunk · Accepted solution]

It might be overkill, but something like this might get it. Try this in a search

..youbase search |rex field=_raw "(?i)parm=mobileNetworkCode=(?P<NEWFEILDNAME>\d+)"

Assuming this line is always formatted like this, and is alwasy a number.

[gokadroid]

Try this if parm is already extracted field with value "xxxx=yyyy", below will get you yyyy:

yourBaseSearchThatExtracts parm
| rex field=parm "\=(?<parmValue>[\S]+)"
| use your parmValue here

UPDATED If you want to extract the key as well:

yourBaseSearchThatExtracts parm
|rex field=parm "(?<parmKey>[^\=]+)\=(?<parmValue>[^\s]+)"| table parmKey, parmValue